Saving clips to files would be a function of whatever sound library you're using. The waveform timeline just provides the selection start and stop times. Saving back to mp3, specifically, would probably require and mp3 encoder which doesn't come with bass
or NAudio (it's a bit of a licensing problem). Saving a region to WAV, however, shouldn't be too difficult. Check out the documentation for the sound library you're using.

The 1 minute tick intervals on the display are currently hardcoded into the library. They're not actually always 1 minute - they're less if the file is smaller or more if it is longer. You could customize that behavior by altering the source.